Semiconductor processing reactor and components thereof

A gas delivery system for delivering at least one process gas to a reaction chamber, the gas delivery system comprising:

• a diffuser in fluid communication with said reaction chamber, said diffuser being attached directly to an upper surface of said reaction chamber, wherein a diffuser volume for distributing said at least one process gas is defined between said diffuser and said upper surface of said reaction chamber, and wherein said reaction chamber comprises opposing side edges and a centerline, wherein said diffuser comprises a plurality of distribution surfaces, a deflecting surface, a first curved side surface, a second curved side surface, and a third curved side surface, wherein the third curved side surface comprises a curve in a lateral direction, and
• wherein said diffuser comprises an increasing lateral width between the first curved side surface and the second curved side surface, wherein a first and a second distribution surface of the plurality of distribution surfaces are sloped downwards at different angles relative to the upper surface, wherein a third distribution surface of the plurality of distribution surfaces is sloped in a lateral direction with respect to a main flow direction along the centerline to cause the at least one process gas to become distributed laterally between the first curved side surface and the second curved side surface prior to the at least one process gas contacting the deflecting surface, and
• wherein said upper surface comprises a curved inlet slot substantially corresponding to said third curved side surface, wherein gas flow velocities exiting the inlet slot are higher near the opposing side edges relative to a lower gas flow velocity near the centerline.